A highly flexible catheter with forward-looking, volumetric ultrasound imaging array at its tip would be invaluable for guiding interventions in totally occluded arteries and in the heart. While new catheter designs have been developed, current Intravascular ultrasound (IVUS) and intra cardiac echocardiography (ICE) systems are either side-looking or do not generate the true volumetric images directly in front of the catheter. A donut disk shaped ultrasound imaging array with a hollow center allowing for guidewire and other intervention tools can provide volumetric imaging capability in front of the catheter with small number of electrical connection using synthetic aperture beamforming methods. We use capacitive micromachined ultrasonic transducer (CMUT) technology in an innovative way to form these 2-D arrays with separate transmit and receive elements. This approach not only results in simpler electronics, but allows one to shape and locate the array elements on the available silicon area to increase transmit power, imaging speed and possibly reduce cross-talk. As important, our research shows that one can integrate all the required transmit and receive electronics on the same silicon chip as the CMUT array. This approach eliminates the large number of chip-to- chip electrical connections and enables direct interface to a reduced number of cables (10-12) in a catheter with a simple flex-tape interconnect. In addition to these manufacturing advantages, the extremely low profile of the fully integrated CMUT array - essentially a 1mm thick disk -- will result in flexible structures to navigate through tortuous arteries and should be easier to integrate to a variety of existing deflectable guide catheters. In this project, we will develop single chip CMUT arrays with fully integrated electronics on 1.5mm and 2.5mm diameter hollow silicon chips operating at 10-20MHz frequency range for forward-looking IVUS and ICE applications. The integrated CMOS electronics will be low-power (<150mW) and will feature integrated temperature sensing for safe operation. We will explore the potential of this approach for improved image quality through novel array designs. We will form catheter tips with CMUT arrays and characterize their performance on custom imaging targets with direct comparison to existing side-looking IVUS catheters. We expect this study to be an important step in translating CMUT technology to clinical settings for cardiology applications. PUBLIC HEALTH RELEVANCE: This study will develop ultimately miniaturized ultrasonic imaging devices that can be attached at the tip of a catheter to guide interventions in coronary arteries and in the heart by providing a volumetric image directly in front of the catheter. This will help increase the success rate of interventions especially in totally blocked arteries and trans- catheter operations in the heart.